莫拉克颱風造成高屏溪流域橋梁損壞之空間分布特性探討

Study on the Space Distribution Characteristics of Damaged Bridges along Gaoping River Watershed on Cause of Typhoon Morakot

邱永芳(Yung-Fang Chiu) ； 黃進國(Chin-Kuo Huang) ； 林雅雯(Ya-Wen Lin) ； 陳家隆(Jia-Long Chen)

《中國土木水利工程學刊》 25卷1期 (2013/03) Pp. 57-69

https://doi.org/10.6652/JoCICHE.201303_25(1).0006

摘要

2009 年莫拉克颱風引發之降雨量為歷年之最，且超過2000年重現期降雨量。使得高屏溪流域發生多處山崩、堰塞湖、土石流，導致河道嚴重變形，多處橋梁及道路損毀。基於臺灣地形分佈特性、地質脆弱性與組成型態及水文特性皆屬相類似之根由，爰此本文運用莫拉克颱風期間造成高屏溪流域跨河橋梁破壞之災損因子資料進行空間分布特性探討研析，以提供山區跨河橋梁選址之參據。主要討論之災損因子包括雨量、水位、堰塞湖、崩塌地、土石流、河川蜿蜒性、土方變化量與坡度變化等。由觀測資料顯示災損橋梁主要集中在高程700公尺以下。而依據災損因子之複合性約略將橋梁破壞特性以高程300公尺和100公尺作為分界點，在高程300公尺以上橋梁多屬於土石流伴隨高複合性災損因子導致橋梁損壞；而高程300公尺至100公尺間之橋梁多為土石流伴隨低複合性災損因子導致橋梁損壞；在高程100公尺以下的橋梁則較偏向於單純沖刷問題導致橋梁破壞，同時本文提出山區橋梁選址時配合水文與地文特性之重要選址原則。

關鍵字

莫拉克 ； 土石流 ； 崩塌地 ； 堰塞湖

並列摘要

The rainfall caused by Typhoon Morakot in 2009 was the most severe one and its amount has surpassed that of 2000 years return period flood. This has resulted in landslides, natural debris dams, and mudflows, which caused severe redirection of water channels and destruction of many bridges and roads. The aim of this paper is to study the characteristics of spacial distribution of damaged bridges caused by Typhoon Morakot along the Gaoping River. The main factors causing damage to be discussed include the rainfall, water level, natural debris dams, landslide, mudflow, river sinuosity, earthwork, and slope change, etc. It was revealed from the collected data that the altitude of most of the damaged bridges is below 700 m. Based on the damage factors, the causes of damaged bridges can be grouped with boundary altitude of 300 m and 100 m. For bridges with altitude higher than 300 m, the damages were mainly caused by mudflows with high complexity. For bridges with altitude between 300 m and 100 m, the damages were mainly caused by mudflows with low complexity. And for bridges with altitude lower than 100 m, the damages were mainly caused by simple scouring problem.

並列關鍵字

morakot ； mudflows ； landslide ； quake lake